The use of synthetic insecticides to control insect pests in crops is a universal practice. This practice has gained a high degree of commercial success because it has been shown that such control can increase crop yield. However, effective use of insecticides requires sound management in view of insect resistance and environmental and worker exposure concerns. One solution applied to this problem has been the provision of new, more highly active insecticides in order to reduce the need for older acutely toxic insecticides and to reduce environmental loading rates.
One new class of insecticides that is gaining significant recognition in the market place is the so-called “neonicotinoid” insecticides. Insecticides of this class include nitroimino- or nitroguanidino-compounds, for example, the compounds imidacloprid, acetamiprid, and thiamethoxam that are described in U.S. Pat. Nos. 4,742,060 and 5,304,566 and EP580553A2, respectively.
Direct treatment of plant propagation materials (such as seeds) with insecticides are target applications which address the need for a reduction of environmental and worker exposure and pest resistance buildup when applied alone or in conjunction with foliar or furrow insecticide applications.
Seed treatments are used on a large variety of crops to control a large variety of pests. Seed treatments are commonly used to ensure uniform stand establishment and reducing yield loss by protecting the seedling against soil-borne insects. Systemic seed treatments may provide an alternative to traditional broadcast sprays of foliar insecticides in some instances.
Insecticide seed treatments come in a variety of formulations: dry flowables (DF), liquid flowables (LF), true liquids (TL), emulsifiable concentrates (EC), dusts (D), wettable powders (WP), suspoemulsions (SE), water-dispersible granules (WG) and others. Some are registered for use only by commercial applicators using closed application systems, others are readily available for on-farm use as dusts, slurries, water-soluble bags, or liquid ready-to-apply formulations.
Commercial seed treatment is often desirable due to the specialized equipment required to properly apply treatments or to treat large volumes of seed. An important concern of the commercial treater is equipment performance to ensure the delivery of a proper amount of active ingredient to the seed. This has become especially important with more modern insecticides that require only very small amounts of material (down to 1 g active ingredient per hundred weight of seed).
Conveniently, many seed treatment materials also are available for on-farm use. These are known as hopper-box or planter-box treatments wherein liquid or dry formulations are applied to seed as it passes through an auger from the transport bin or truck to the planter boxes. These formulations are a very convenient way to apply seed treatment onto bulk seed right before planting. Conventional dry treatments generally are formulated with talc or graphite which adheres the treatment chemical to the seed. Conventional liquid hopper-box treatments generally are made available as a fast-drying formulations. In any case, good seed coverage is required for maximum benefit from any seed treatment formulation.
However, obtaining thorough seed coverage can be difficult when attempting to treat seed. For example, dry formulations can present unacceptable worker exposure to the insecticidal active ingredient. Certain liquid formulations can become inhomogeneous on storage, such that particle size or viscosity do not remain constant. Additional problems can arise such as unacceptable drying times, material build-up in the seed treater, low seed flowability, poor seed coverage and dust-off of the insecticide from the seed prior to planting. As a result, handling is rendered difficult and the biological efficacy of the seed treatment is reduced.
There is a need in the art for alternative new liquid insecticidal seed treatment compositions that are effective for use with both commercial and on-farm seed treatment equipment.